Mirror galvanometer



Dec. 26, 1961 s. GCTZE ET AL MIRROR GALVANOMETER Filed Feb. 26. 1959 United States Patent ()fitice 3,0l5,% Patented Dec. 26, 1961 3,0l5,ll65 MHRRGR GALVANOME'I'ER iegfried Giitze and Wilhelm .Fritzsch, Franlnurt am Main, Germany, assignors to lrlartmann Brains Airtieugesellschaft, Frankfurt am Main, Germany Filed Feb. 26, 1959, Ser. No. 795,815 Qlaimspriority, application Germany Mar. 6, 1958 2 Claims. (till. 324 154) The invention relates to a mirror galvanorneter used for rapid current changes. The object of the invention is to provide a rigid connection between the measuring coil and the mirror even if the latter is arranged above the coil and in a known manner with the shaft of the system consisting of the coil and mirror passing the center of mass or" the mirror. Furthermore the invention solves the problem of keeping the moment of inertia of the oscillating system as small as possible for enabling a maximum inherent frequency for a given directive force.

The invention is set forth in the drawing wherein:

FIG. 1 is a longitudinal sectional view of the coil and mirror and mounting means therefor;

FIGS. 2 and 3 are enlarged side and front views respectively of the coil and mirror system;

FIG. 4 is a transverse sectional view of the invention, the section being taken along the line 4-4 of REG. 1 looking in the direction of the arrows of said line; and

FIGS. 5 and 6 are transverse sectional views taken along the respective lines 55 and 6-6 looking in the direction of the arrows of said lines.

In the drawing a hollow mount lower portions P and P of the invention.

The system consisting of a coil 1 and mirror 2 is sus pended between strips 3, 3 which are fastened to springs 4. The tension of strips 3, 3' for torsional stress can be adjusted by means of screw 5 arranged in the threaded nut member 8. Longitudinal displacement of the nut member 8 is possible, however it cannot be rotated between the two jaws 9 on the upper portion. The nut member 8 is secured by a screw 7 after having its position adjusted for tension of the stress. The head of screw 5 rests on the upper edge of jaw 9. Coil l is arranged in the field of a permanent magnet (not shown) acting on pole pieces lit and 11. The mount has a window 12 for the ligh beam to be deflected by mirror 2.

Four thin and rather stiff wires or filaments 13, 14, 15, 16 of elastic material such as metal glass or quartz, which can be bent to the shown configuration are glued or fixed in some other way to the flange surface of coil 1.

At each flange side the wires should be arranged far apart; as shown by FIGS. 2 and 6 they are approximately in the center of the vertical parts of the coil flanges. Each two opposite pairs of wire (13, 14 and 15, 16 in the drawing) are fixed just above the coil at a narrow side of the mirror, e.g. also by gluing or cementing, the wires of each pair fitting tightly to each other. Above the mirror M having upper and carries the essential components all the four wires are combined in socket 17 and below the moving coil in socket E8. The sockets are again fixed to strips 3, 3, e.g. glued on.

Current supply is via strips 3, 3 which for this purpose are extended beyond sockets l7 and i8 and which at 19 and 2d are soldered to the ends of the moving coil as at S. l' the Wires are of metal the cement or adhesive may be of insulating material to prevent short circuiting of the coil. Of course metal wires could be discontinued at the zone of the mirror or coil.

Instead of fastening the pairs of wire l3, l4 and 15, 16 to the two narrow sides of the mirror as shown in the drawing it is also possible to fasten wires l3, l5 and 1 5, in to the mirror. In this case only the position of the reflector surface to the coil winding axis changes.

A coil'rnirror system as covered by the invention is fitted with an extremely rigid and safe connection between the coil and the mirror. Moreover, the moment of inertia of the whole system referred to the axis of oscillation, mainly determined by the coil and the mirror as well as well as the thin wires, will hardly be increased.

The invention claimed is:

1. A galvanometer comprising a pair of substantially longitudinally alined tension strips having inner end portions respectively projecting toward each other, and means for mounting the strips, magnet pole pieces in the zone between the strips, a coil to turn about axis substantially in line with the strips and between the pole pieces and having exterior frontal faces extending substantially in a direction common with that of the strips, :1 flat rectangular mirror situated between the coil and one of the strips, and spaced from the coil, and two pairs of wirelike members substantially extending from one strip to the other and adhered together and secured thereto at their respective end portions, each pair of said members being respectively secured on one of said frontal faces and on said mirror at opposite edge portions thereof, the four members being spaced from each other in the zone between coil and the mirror to form a substantially rigid connection between the coil and mirror for substantially quantitative transmission of turning motion from the coil to the mirror when the portions of said members between the coil and mirror are under tension from said strips.

2. A galvanometer as claimed in claim 1, the members, coil and mirror being substantially symmetrical about said axis.

References Cited in the file of this patent UNITED STATES PATENTS 1,197,460 Dixon Sept. 5, 1916 1,397,441 Miller Nov. 15, 1921 2,131,478 Mann Sept. 27, 1938 2,510,585 Kellogg June 6, 1950 2,519,591 Morrow Aug. 22, 1950 2,599,661 Richardson June 10, 1952 

